This invention relates to gas-turbine combustion chambers with combustion chamber tiles, where the combustion chamber tiles are fastened to a supporting structure of the combustion chamber outer was.
The combustion chamber tiles have an arbitrary number (very high, often in the thousands) of effusion cooling holes on the side facing the combustion chamber. These effusion cooling holes are used to cool the tile against the high temperatures in the combustion chamber. Moreover, at least one mixing air hole is located on the combustion chamber tile and is used to pass air from the space (annulus) surrounding the combustion chamber on the outside into the combustion chamber, for the purpose of cooling the combustion and making it lean, thereby reducing the amount of NOx generated. In addition to cooling by the effusion cooling holes, the tiles are frequently also provided with a ceramic coating acting as an insulating layer against the high temperatures in the combustion chamber.
This arrangement is known from the state of the art, cf. EP 972 992 B1 or DE 102 14 570 A1.
These admixing holes are mostly designed as a funnel or tube projecting into the combustion chamber, thus forming a flow-guiding element (FIG. 3).
Tiles of this type are usually manufactured either by casting, coating with a ceramic layer and drilling of the effusion cooling holes (e.g. with laser), by casting, drilling and coating, or by additive manufacturing methods such as selective laser sintering, direct laser depositioning or electron-beam build-up welding. With the additive methods, the effusion cooling holes are made directly in the tile, and expensive drilling is not required.
When using additive methods to manufacture the tile with admixing holes protruding from the tile as shown in FIG. 4, an auxiliary structure to prevent downward sagging of the admixing hole geometry during the manufacturing process is needed in the case of a vertical arrangement of the tiles in the production machine.
A sub-structure of this type has considerable disadvantages a) it is material-intensive, b) it prolongs the manufacturing process, and c) it has to be removed from the tile after manufacture, which is very cost-intensive. To avoid this, a horizontal manufacture is frequently chosen, which has the disadvantage that fewer components can be manufactured in one operation, leading to substantially higher costs per component. A further alternative would be to provide the admixing hole geometry projecting into the combustion chamber in a further step, but this too involves costs.